Broadband cable network utilizing common bit-loading

ABSTRACT

A network for determining a common bit-loading modulation scheme for communicating between nodes in the network is disclosed. The network may include a transmitting node within the plurality of nodes where the transmitting node is capable of sending a probe signal to the nodes, and at least one receiving node within the plurality of nodes in signal communication with the transmitting node. The at least one receiving node is capable of transmitting a first response signal in response to receiving the probe signal. The first response signal includes a first bit-loading modulation scheme determined by the at least one receiving node. The transmitting node is further capable of determining the common bit-loading modulation scheme from the first response signal.

REFERENCE TO EARLIER-FILED APPLICATIONS

This application is a continuation of application Ser. No.14/082,544filed on Nov. 18, 2013, which is a continuation of 13/027,030,titled “Broadband Cable Network Utilizing Common Bit-Loading,” filedFeb. 14, 2011, which is a continuation of application Ser. No.10/889,975 titled “Broadband Cable Network Utilizing CommonBit-Loading,” filed Jul. 12, 2004, now U.S. Pat. No. 7,889,759, which isa continuation-in-part of application Ser. No. 10/778,505, titled“Network Interface Device and Broadband Local Area Network Using CoaxialCable,” filed Feb. 13, 2004, now abandoned, which is a continuation ofU. S. Utility application Ser. No. 09/910,412titled “Network InterfaceDevice and Broadband Local Area Network Using Coaxial Cable,” filed Jul.21, 2001, now U.S. Pat. No. 7,594,249, which claims the benefit of U.S.Provisional Application Ser. No. 60/288,967, titled “Network Interfaceand Broadband Local Area Network Using Coaxial Cable,” filed May 4,2001, all of which are incorporated here by reference in theirentireties to provide continuity of disclosure. Application Ser. No.13/027,030, titled “Broadband Cable Network Utilizing CommonBit-Loading,” filed Feb. 14, 2011, is also a continuation-in-part of U.S. application Ser. No. 10/322,834, titled “Broadband Network forCoaxial Cable Using Multi-carrier Modulation,” filed Dec. 18, 2002, nowU.S. Pat. No. 7,295,518, which is a continuation of U. S. applicationSer. No. 10/230,687, titled “Broadband Network for Coaxial Cable UsingMulti-carrier Modulation,” filed Aug. 29, 2002, now abandoned, whichclaims the benefit of the following U. S. Provisional Applications: (a)Ser. No. 60/316,820 titled “Broadband Local Area Network Using CoaxialCable,” filed Aug. 30, 2001; (b) Ser. No. 60/363,420 titled “Method ofBit and Energy Loading to Reduce Interference Effects in Devices Sharinga Communication Medium,” filed Mar. 12, 2002; and (c) Ser. No.60/385,361 titled “Power Loading to Reduce Interference Effects inDevices Sharing a Communication Medium,” filed Jun. 3, 2002, all ofwhich applications are incorporated here by reference in theirentireties to provide continuity of disclosure.

BACKGROUND OF THE INVENTION

Field of Invention

The invention relates to broadband communication networks, and inparticular to broadband communication networks utilizing coaxial cable.

Related Art

The worldwide utilization of external television (“TV”) antennas forreceiving broadcast TV, and of cable television and satellite TV isgrowing at a rapid pace. These TV signals from an external TV antenna,cable TV and satellite TV (such as from direct broadcast satellite “DBS”system) are usually received externally to a building (such as a home oran office) at a point-of-entry (“POE”). There may be multiple TVreceivers and/or video monitors within the building and these multipleTV receivers may be in signal communication with the POE via a broadbandcable network that may include a plurality of broadband cables andbroadband cable splitters. Generally, these broadband cable splittersdistribute downstream signals from the POE to various terminals (alsoknown as “nodes”) in the building. The nodes may be connected to varioustypes of customer premise equipment (“CPE”) such as cable converterboxes, televisions, video monitors, cable modems, cable phones and videogame consoles.

Typically, these broadband cables and broadband cable splitters areimplemented utilizing coaxial cables and coaxial cable splitters,respectively. Additionally, in the case of cable TV or satellite TV, themultiple TV receivers may be in signal communication with the broadbandcable network via a plurality of cable converter boxes, also known asset-top boxes (“STBs”), that are connected between the multiple TVreceivers and the broadband cable network via a plurality of networknodes.

Typically, a STB connects to a coaxial cable from a network node (suchas the wall outlet terminal) to receive cable TV and/or satellite TVsignals. Usually, the STB receives the cable TV and/or satellite TVsignals from the network node and converts them into tuned TV signalsthat may be received by the TV receiver and/or video signals that may bereceived by a video monitor.

In FIG. 1, an example known broadband cable network 100 (also known as a“cable system” and/or “cable wiring”) is shown within a building 102(also known as customer premises or “CP”) such as a typical home oroffice. The broadband cable system 100 may be in signal communicationwith an optional cable service provider 104, optional broadcast TVstation 106, and/or optional DBS satellite 108, via signal path 110,signal path 112 and external antenna 114, and signal path 116 and DBSantenna 118, respectively. The broadband cable system 100 also may be insignal communication with optional CPEs 120, 122 and 124, via signalpaths 126, 128 and 130, respectively.

In FIG. 2, another example known broadband cable system is shown withina building (not shown) such as a typically home. The cable system 200may be in signal communication with a cable provider (not shown),satellite TV dish (not shown), and/or external antenna (not shown) via asignal path 202 such as a main coaxial cable from the building to acable connection switch (not shown) outside of the building. The cablesystem 200 may include a POE 204 and main splitter 206, a sub-splitter208, and STBs A 210, B 212 and C 214.

Within the cable system 200, the POE 204 may be in signal communicationwith main splitter 206 via signal path 216. The POE 204 may be theconnection point from the cable provider which is located external tothe building of the cable system 200. The POE 202 may be implemented asa coaxial cable connector, transformer and/or filter.

The main splitter 206 may be in signal communication with sub-splitter208 and STB A 210 via signal paths 218 and 220, respectively. Thesub-splitter 208 may be in signal communication with STB B 212 and STB C214 via signal paths 222 and 224, respectively. The main splitter 206and sub-splitter 208 may be implemented as coaxial cable splitters. TheSTB A 210, B 212 and C 214 may be implemented by numerous well known STBcoaxial units such as cable television set-top boxes and/or satellitetelevision set-top boxes. Typically, the signal paths 202, 216, 218,220, 222 and 224 may be implemented utilizing coaxial cables.

In an example operation, the cable system 200 would receive CATV, cableand/or satellite radio frequency (“RF”) TV signals 226 via signal path202 at the POE 204. The POE 204 may pass, transform and/or filter thereceived RF signals to a second RF signal 228 that may be passed to themain splitter 206 via signal path 216. The main splitter 206 may thensplit the second RF signal 228 into split RF signals 230 and 232. Thesplit RF signal 230 is then passed to the sub-splitter 208 and the splitRF signal 232 is passed to the STB A 210 via signal paths 218 and 220,respectively. Once the split RF signal 232 is received by the STB A 210,the STB A 210 may convert the received split RF signal 232 into abaseband signal 238 that may be passed to a video monitor (not shown) insignal communication with the STB A 210.

Once the split RF signal 230 is received by the sub-splitter 208, thesub-splitter 208 splits the received split RF signal 230 into sub-splitRF signals 234 and 236 that are passed to STB B 212 and STB C 214 viasignal paths 222 and 224, respectively. Once the sub-split RF signals234 and 236 are received by the STB B 212 and STB C 214, respectively,the STB B 212 and STB C 214 may convert the received sub-split RFsignals 234 and 236 into baseband signals 240 and 242, respectively,that may be passed to video monitors (not shown) in signal communicationwith STB B 212 and STB C 214.

As the utilization of the numbers and types of CPEs in buildingsincrease (such as the number of televisions, video monitors, cablemodems, cable phones, video game consoles, etc., increase in a typicalhome or office environment), there is a growing need for different CPEsto communicate between themselves in a network type of environmentwithin the building. As an example, users in a home may desire to playnetwork video games between different rooms in home environmentutilizing the coaxial cable network installed throughout the home.Additionally, in another example, users in a home may want to shareother types of digital data (such video and/or computer information)between different rooms in a home.

Unfortunately, most broadband cable networks (such as the examples shownin both FIG. 1 and FIG. 2) presently utilized within most existingbuildings are not configured to allow for easy networking between CPEsbecause most broadband cable networks utilize broadband cable splittersthat are designed to split an incoming signal from the POE into numeroussplit signals that are passed to the different nodes in different rooms.

As an example, in a typical home the signal splitters are commonlycoaxial cable splitters that have an input port and multiple outputports. Generally, the input port is known as a common port and theoutput ports are known as tap ports. These types of splitters aregenerally passive devices and may be constructed using lumped elementcircuits with discrete transformers, inductors, capacitors, andresistors and/or using strip-line or microstrip circuits. These types ofsplitters are generally bi-directional because they may also function assignal combiners, which sum the power from the multiple tap ports into asingle output at the common port.

However, presently many CPEs utilized in modern cable and DBS systemshave the ability to transmit as well as receive. If a CPE is capable oftransmitting an upstream signal, the transmitted upstream signal fromthat CPE typically flows through the signal splitters back to the POEand to the cable and/or DBS provider. In this reverse flow direction,the signal splitters function as signal combiners for upstream signalsfrom the CPEs to the POE. Usually, most of the energy from the upstreamsignals is passed from the CPEs to the POE because the splitterstypically have a high level of isolation between the different connectedterminals resulting in significant isolation between the various CPEs.

The isolation creates a difficult environment to network between thedifferent CPEs because the isolation results in difficulty fortransmitting two-way communication data between the different CPEs.Unfortunately, CPEs are becoming increasingly complex and a growingnumber of users desire to connect these multiple CPEs into differenttypes of networks.

Therefore, there is a need for a system and method to connect a varietyof CPEs into a local network, such as local-area network (“LAN”), withina building such as a home or office. Additionally, there is a need for asystem and method to connect a variety of CPEs into a local network,such as a LAN, within a building such as a home or office while allowingthe utilization of an existing coaxial cable network within thebuilding.

SUMMARY

A broadband cable network (“BCN”) for determining a common bit-loadingmodulation scheme for communicating between a plurality of nodes in theBCN is disclosed. The BCN may include a transmitting node within theplurality of nodes where the transmitting node is capable of sending aprobe signal to the plurality of nodes, and at least one receiving nodewithin the plurality of nodes in signal communication with thetransmitting node. The at least one receiving node is capable oftransmitting a first response signal in response to receiving the probesignal. The first response signal includes a first bit-loadingmodulation scheme determined by the at least one receiving node. Thetransmitting node is further capable of determining the commonbit-loading modulation scheme from the first response signal.

The BCN may further include a sub-plurality of receiving nodes withinthe plurality of nodes wherein the sub-plurality of receiving nodes arecapable of transmitting a sub-plurality of response signals in responseto receiving the probe signal. The sub-plurality of response signals mayinclude other bit-loading modulation schemes and each bit-loadingmodulation scheme may be determined by a receiving node within thesub-plurality of receiving nodes. The transmitting node may be capableof determining the common bit-loading modulation scheme from the firstresponse signal and the sub-plurality of response signals.

As an example of operation, the BCN is capable of transmitting a probesignal from the transmitting node to the plurality of receiving nodesand receiving a plurality of response signals from the correspondingreceiving nodes of the plurality of receiving nodes, wherein each of theresponse signals includes a bit-loading modulation scheme determined bythe corresponding receiving node. The BCN is further capable ofdetermining the common bit-loading modulation scheme from the receivedplurality of response signals.

Other systems, methods, features and advantages of the invention will beor will become apparent to one with skill in the art upon examination ofthe following figures and detailed description. It is intended that allsuch additional systems, methods, features and advantages be includedwithin this description, be within the scope of the invention, and beprotected by the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingfigures. The components in the figures are not necessarily to scale,emphasis instead being placed upon illustrating the principles of theinvention. In the figures, like reference numerals designatecorresponding parts throughout the different views.

FIG. 1 shows a block diagram of an example implementation of a knownbroadband cable system within a building.

FIG. 2 shows a block diagram of another example implementation of aknown broadband cable system within the building shown in FIG. 1.

FIG. 3 shows a block diagram of an example implementation of a broadbandcable network (“BCN”) within a building.

FIG. 4 shows a functional diagram showing the communication between thedifferent nodes shown in the BCN of FIG. 3 in a unicast mode.

FIG. 5 shows another functional diagram showing the communicationbetween the different nodes shown in the BCN of FIG. 3 in a broadcastmode.

FIG. 6 shows a block diagram of an example implementation of the BCNshown in FIG. 3 when node A is communicating to node B.

FIG. 7 shows a block diagram of another example implementation of theBCN shown in FIG. 3 when node A is communicating to node C.

FIG. 8 shows a block diagram of an example implementation of the BCNshown in FIG. 3 when node C is communicating to node B.

FIG. 9 shows a plot of the transfer function versus frequency for thechannel path between node A and node B and the channel path between nodeA and node C shown in both FIGS. 6 and 7.

FIG. 10A shows a plot of the bit-loading constellation versus carriernumber for the channel path between node A and node B shown in FIG. 9.

FIG. 10B shows a plot of the bit-loading constellation versus carriernumber for the channel path between node A and node C shown in FIG. 9.

FIG. 10C shows a plot of the bit-loading constellation versus carriernumber for the resulting broadcast channel path between node A and nodeB and node A and node C based on the constellations shown in FIGS. 10Aand 10B.

FIG. 11 shows a flowchart illustrating the method performed by the BCNshown in FIG. 3.

DETAILED DESCRIPTION

In the following description of the preferred embodiment, reference ismade to the accompanying drawings that form a part hereof, and in whichis shown by way of illustration a specific embodiment in which theinvention may be practiced. It is to be understood that otherembodiments may be utilized and structural changes may be made withoutdeparting from the scope of the present invention.

In FIG. 3, a block diagram of an example implementation of a broadbandcable network (“BCN”) 300 utilizing common bit-loading within a customerpremises (“CP”) 302 is shown. The CP 302 may be a building such as ahome or office having a plurality of customer premises equipment (“CPE”)304, 306 and 308 in signal communication with the BCN 300 via aplurality of corresponding CPE signal paths 310, 312 and 314. The BCN300 may be in signal communication optionally with an external antenna(not shown), cable provider (not shown) and/or direct broadcastsatellite (“DBS”) provider (not shown) via external BCN path 316.

The BCN 300 may include a point-of-entry (“POE”) 320, a splitter network322 and a plurality of nodes such as node A 324, node B 326 and node C328. The splitter network 322 may be in signal communication with thePOE 320, via signal path 330, and the plurality of nodes 324, 326 and328 via signal paths 332, 334 and 336, respectively. The nodes 324, 326and 328 may be in signal communication with the CPEs 304, 306 and 308via signal paths 310, 312 and 314, respectively.

In an example operation, the BCN 300 receives input radio frequency(“RF”) signals from optionally the external antenna (not shown), cableprovider (not shown) and/or direct broadcast satellite (“DBS”) provider(not shown) at the POE 320 via external BCN path 316. The BCN 300 thenpasses the input RF signals from POE 320 to the splitter network 322,via signal path 330, and the splitter network 322 splits the input RFsignal into split RF signals that are passed to the nodes 324, 326 and328 via signal paths 332, 334 and 336, respectively. It is appreciatedby those skilled in the art that the BCN 300 may be implemented as acoaxial cable network utilizing coaxial cables and components.

In FIG. 4, a functional diagram 400 showing the communication betweenvarious nodes 402, 404 and 406 corresponding to the nodes in the BCN300, FIG. 3, is shown. The nodes 402, 404 and 406 may be interconnectedbetween node pairs utilizing corresponding inter-node channels betweenthe node pairs. It is appreciated by those skilled in the art that evenif the nodes are individually connected with one another via a signalinter-node channel between the node pairs, each inter-node channelbetween node pairs may be asymmetric. Therefore, inter-node channelsbetween node A 402, node B 404 and node C 406 may be asymmetric andtherefore utilize different bit-loading modulation schemes depending onthe direction of the signals between the nodes. As a result, thetypically asymmetric inter-node channels between node A 402, node B 404and node C 406 may be described by the corresponding direction-dependentnode channels AB, BA, AC, CA, BC and CB.

As an example, node A 402 is in signal communication with node B 404 viasignal paths 408 and 410. Signal path 408 corresponds to the AB channeland signal path 410 corresponds to the BA channel. Additionally, node A402 is also in signal communication with node C 406 via signal paths 412and 414. Signal path 412 corresponds to the AC channel and signal path414 corresponds to the CA channel. Similarly, node B 404 is also insignal communication with node C 406 via signal paths 416 and 418.Signal path 416 corresponds to the BC channel and signal path 418corresponds to the CB channel.

In this example, the AB channel corresponds to the channel utilized bynode A 402 transmitting to node B 404 along signal path 408. The BAchannel corresponds to the reverse channel utilized by node B 404transmitting to node A 402 along signal path 410. Similarly, the ACchannel corresponds to the channel utilized by node A 402 transmittingto node C 406 along signal path 412. The CA channel corresponds to thereverse channel utilized by node C 406 transmitting to node A 402 alongsignal path 414. Moreover, the BC channel corresponds to the channelutilized by node B 404 transmitting to node C 406 along signal path 416.The CB channel corresponds to the reverse channel utilized by node C 406transmitting to node B 404 along signal path 418.

In example of operation, in order for node A 402 to transmit the samemessage to both node B 404 and node C 406 using the AB channel alongsignal path 408 and AC channel along signal path 412, node A 402 willneed to transmit (i.e., “unicast”) the same message twice, once to nodeB 404 and a second time to node C 406 because channel AB and channel ACmay utilize different bit-loading modulation schemes.

In FIG. 5, another functional diagram 500 showing the communicationbetween various nodes 502, 504 and 506 corresponding to the nodes in theBCN 300, FIG. 3, is shown. In FIG. 5, node A 502 may transmit a messagein a broadcast mode (also known as a “multicast” mode) simultaneously tonode B 504 and node C 506 using an A-BC channel via signal path 508. Themessage transmission utilizing the A-BC channel, along signal path 508,is the equivalent of simultaneously transmitting a broadcast messagefrom node A 502 to node B 504 via an AB channel along signal path 510and to node C 506 via an AC channel along signal path 512 in a fashionthat is similar to transmission described in FIG. 4. However, in orderto insure that both node B 504 and node C 506 receive the transmissionsbroadcast signal from node A 502, node A 502 utilizes a bit-loadingmodulation scheme that is known as a common bit-loaded modulationscheme. The common bit-loaded modulation scheme transmitted via the A-BCchannel, along signal path 508, is a combination of the bit-loadingmodulation scheme transmitted via the AB channel, along signal path 510,and the AC channel, along signal path 512.

It is appreciated by those skilled in the art that the differentchannels typically utilize different bit-loading modulation schemesbecause the channels are physically and electrically different in thecable network. Physically the channels typically vary in length betweennodes and electrically vary because of the paths through and reflectionsfrom the various cables, switches, terminals, connections and otherelectrical components in the cable network. Bit-loading is the processof optimizing the bit distribution to each of the channels to increasethroughput. A bit-loading scheme is described in U.S. Utilityapplication Ser. No. 10/322,834 titled “Broadband Network for CoaxialCable Using Multi-carrier Modulation,” filed Dec. 18, 2002, which isincorporated herein, in its entirety, by reference.

The BCN may operate with waveforms that utilize bit-loaded orthogonalfrequency division multiplexing (OFDM). Therefore, the BCN may transmitmultiple carrier signals (i.e., signals with different carrierfrequencies) with different QAM constellations on each carrier. As anexample, over a bandwidth of about 50 MHz, the BCN may have 256different carriers which in the best circumstances would utilize up to256 QAM modulation carriers. If instead the channel is poor, the BCN mayutilize BPSK on all the carriers instead of QAM. If the channel is goodin some places and poor in others, the BCN may utilize high QAM in someparts and lower types modulation in others.

As an example, in FIG. 6, a block diagram of an example implementationof the BCN 600 is shown. The BCN 600 may be in signal communication witha cable provider (not shown), satellite TV dish (not shown), and/orexternal antenna (not shown) via a signal path 602 such as a maincoaxial cable from the customer premises to a cable connection switch(not shown) outside of the customer premises.

The BCN 600 may include a POE 604 and main splitter 606, a sub-splitter608, nodes A 610, B 612 and C 614, and STBs A 616, B 618 and C 620.Within the BCN 600, the POE 604 may be in signal communication with mainsplitter 606 via signal path 622. The POE 604 may be the connectionpoint from the cable provider which is located external to the customerpremises of the BCN 600. The POE 604 may be implemented as a coaxialcable connector, transformer and/or filter.

The main splitter 606 may be in signal communication with sub-splitter608 and node C 614 via signal paths 624 and 626, respectively. Thesub-splitter 608 may be in signal communication with node A 610 and nodeB 612 via signal paths 628 and 630, respectively. The main splitter 606and sub-splitter 608 may be implemented as coaxial cable splitters. NodeA 610 may be in signal communication with STB A 616 via signal path 632.Similarly, node B 612 may be in signal communication with STB B 618 viasignal path 634. Moreover, node C 614 may be in signal communicationwith STB C 620 via signal path 636. STBs A 616, B 618 and C 620 may beimplemented by numerous well known STB coaxial units such as cabletelevision set-top boxes and/or satellite television set-top boxes.Typically, the signal paths 602, 622, 624, 626, 628, 630, 632, 634 and636 may be implemented utilizing coaxial cables.

As an example of operation, if node A 610 transmits a message to node B612, the message will propagate through two transmission paths from nodeA 610 to node B 612. The first transmission path 640 travels from node A610 through signal path 628, sub-splitter 608 and signal path 630 tonode B 612. The second transmission path includes transmission sub-paths642 and 644. The first sub-path 642 travels from node A 610 throughsignal path 628, sub-splitter 608, signal path 624, main splitter 606and signal path 622 to POE 604. The second sub-path 644 travels from POE604, through signal path 622, main splitter 606, signal path 624,sub-splitter 608 and signal path 630.

The first transmission path 640 is typically very lossy and experiencesa high amount of attenuation because of the isolation between theoutputs of sub-splitter 608. The second transmission path, however, doesnot experience the attenuation of the first transmission path 640. Thesecond transmission path results from the transmission of message signal646 from node A 610 to the POE 604 along the first sub-path 642 whichresults in a reflected message signal 648 from the POE 604. Thereflected message signal 648 results from impedance mismatches betweenthe POE 604 and the rest of the BCN 600.

As another example, in FIG. 7, another block diagram of an exampleimplementation of the BCN 700 is shown. Similar to FIG. 6, in FIG. 7,the BCN 700 may be in signal communication with a cable provider (notshown), satellite TV dish (not shown), and/or external antenna (notshown) via a signal path 702 such as a main coaxial cable from thecustomer premises to a cable connection switch (not shown) outside ofthe customer premises.

The BCN 700 may include a POE 704 and main splitter 706, a sub-splitter708, nodes A 710, B 712 and C 714, and STBs A 716, B 718 and C 720.Within the BCN 700, the POE 704 may be in signal communication with mainsplitter 706 via signal path 722. The POE 704 may be the connectionpoint from the cable provider which is located external to the customerpremises of the BCN 700. The POE 704 may be implemented as a coaxialcable connector, transformer and/or filter.

The main splitter 706 may be in signal communication with sub-splitter708 and node C 714 via signal paths 724 and 726, respectively. Thesub-splitter 708 may be in signal communication with node A 710 and nodeB 712 via signal paths 728 and 730, respectively. The main splitter 706and sub-splitter 708 may be implemented as coaxial cable splitters. NodeA 710 may be in signal communication with STB A 716 via signal path 732.Similarly, node B 712 may be in signal communication with STB B 718 viasignal path 734. Moreover, node C 714 may be in signal communicationwith STB C 720 via signal path 736. STBs A 716, B 718 and C 720 may beimplemented by numerous well known STB coaxial units such as cabletelevision set-top boxes and/or satellite television set-top boxes.Typically, the signal paths 702, 722, 724, 726, 728, 730, 732, 734 and736 may be implemented utilizing coaxial cables.

As an example of operation, if node A 710 transmits a message to node C714, the message will propagate through two transmission paths from nodeA 710 to node C 714. The first transmission path 740 travels from node A710 through signal path 728, sub-splitter 708, signal path 724, mainsplitter 706 and signal path 726 to node C 714. The second transmissionpath includes transmission sub-paths 742 and 744. The first sub-path 742travels from node A 710 through signal path 728, sub-splitter 708,signal path 724, main splitter 706 and signal path 722 to POE 704. Thesecond sub-path 744 travels from POE 704, through signal path 722, mainsplitter 706, and signal path 726 to node C 714.

The first transmission path 740 is typically very lossy and experiencesa high amount of attenuation because of the isolation between theoutputs of sub-splitter 708 and main splitter 706. The secondtransmission path, however, does not experience the attenuation of thefirst transmission path 740. The second transmission path results fromthe transmission of message signal 746 from node A 710 to the POE 704along the first sub-path 742 which results in a reflected message signal748 from the POE 704. The reflected message signal 748 results frommismatches between the POE 704 and the rest of the BCN 700.

As still another example, in FIG. 8, another block diagram of an exampleimplementation of the BCN 800 is shown. Similar to FIGS. 6 and 7, inFIG. 8, the BCN 800 may be in signal communication with a cable provider(not shown), satellite TV dish (not shown), and/or external antenna (notshown) via a signal path 802 such as a main coaxial cable from thecustomer premises to a cable connection switch (not shown) outside ofthe customer premises.

The BCN 800 may include a POE 804 and main splitter 806, a sub-splitter808, nodes A 810, B 812 and C 814, and STBs A 816, B 818 and C 820.Within the BCN 800, the POE 804 may be in signal communication with mainsplitter 806 via signal path 822. The POE 804 may be the connectionpoint from the cable provider which is located external to the customerpremises of the BCN 800. The POE 804 may be implemented as a coaxialcable connector, transformer and/or filter.

The main splitter 806 may be in signal communication with sub-splitter808 and node C 814 via signal paths 824 and 826, respectively. Thesub-splitter 808 may be in signal communication with node A 810 and nodeB 812 via signal paths 828 and 830, respectively. The main splitter 806and sub-splitter 808 may be implemented as coaxial cable splitters. NodeA 810 may be in signal communication with STB A 816 via signal path 832.Similarly, node B 812 may be in signal communication with STB B 818 viasignal path 834. Moreover, node C 814 may be in signal communicationwith STB C 820 via signal path 836. STBs A 816, B 818 and C 820 may beimplemented by numerous well known STB coaxial units such as cabletelevision set-top boxes and/or satellite television set-top boxes.Typically, the signal paths 802, 822, 824, 826, 828, 830, 832, 834 and836 may be implemented utilizing coaxial cables.

As an example of operation, if node C 814 transmits a message to node B812, the message will propagate through two transmission paths from nodeC 814 to node B 812. The first transmission path 840 travels from node C814 through signal path 826, main splitter 806, signal path 824,sub-splitter 808 and signal path 830 to node B 812. The secondtransmission path includes two transmission sub-paths 842 and 844. Thefirst sub-path 842 travels from node C 814 through signal path 826, mainsplitter 806, and signal path 822 to POE 804. The second sub-path 844travels from POE 804, through signal path 822, main splitter 806, signalpath 824, sub-splitter 808 and signal path 830 to node B 812.

The first transmission path 840 is typically very lossy and experiencesa high amount of attenuation because of the isolation between theoutputs of sub-splitter 808 and main splitter 806. The secondtransmission path, however, does not experience the attenuation of thefirst transmission path 840. The second transmission path results fromthe transmission of message signal 846 from node C 814 to the POE 804along the first sub-path 842 which results in a reflected message signal848 from the POE 804. The reflected message signal 848 results frommismatches between the POE 804 and rest of the BCN 800.

In FIG. 9, a plot 900 of the maximum bit-loading constellation 902versus frequency 904 is shown for the channel path utilized by node A totransmit to node B and the channel path utilized by node A to transmitto node C. Line 906 represents the AB channel and line 908 representsthe AC channel. The AB channel has a null 910 that represents thereflection distance from the POE to node B. The AC channel has nulls 912and 914. Null 912 represents the reflection distance from the POE tonode C and null 914 represents a harmonic that is a multiple value ofthe value of null 912. In general, the nulls are caused by theproperties, e.g., amplitudes and time delays, that are unique to eachtransmission path in the network.

Returning to FIG. 5, the BCN, in order to insure that both node B 504and node C 506 are able to receive a broadcast signal transmitted fromnode A 502, utilizes a bit-loading modulation scheme that is known asthe common bit-loaded modulation scheme. The common bit-loadedmodulation scheme transmitted via the A-BC channel, along signal path508, is a combination of the bit-loading modulation scheme transmittedvia the AB channel, along signal path 510, and the AC channel, alongsignal path 512.

Therefore, in FIG. 10A, a plot 1000 of carrier frequency signals ofvarious bit-loading constellations 1002 versus carrier number 1004 forthe AB channel path between node A and node B is shown. Line 1006represents the AB channel and follows an envelope of the constellationsizes of the 8 different carrier number signals within the AB channel.As an example, within the AB channel carrier number signals 1 and 8 maytransmit at a constellation size of 256 QAM, carrier number signals 2, 3and 7 may transmit at a constellation size of 128 QAM, carrier numbersignals 4 and 6 may transmit at a constellation size of 64 QAM, andcarrier number signal 5 may be OFF (i.e., no carrier signal of anyconstellation size may be transmitted because of the null in the channelcharacteristics).

Similarly in FIG. 10B, a plot 1008 of carrier frequency signals ofvarious bit-loading constellations 1010 versus carrier number 1012 forthe AC channel path between node A and node C is shown. Line 1014represents the AC channel and follows an envelope of the constellationsizes of the 8 different carrier number signals within the AC channel.As an example, within the AC channel carrier number signals 1, 2, 4, 6and 8 may transmit at a constellation size of 128 QAM, carrier numbersignal 5 may transmit at a constellation size of 256 QAM, and carriernumber signals 3 and 7 may be OFF (again, no carrier signals may betransmitted because of nulls in the channel characteristics).

In FIG. 10C, a plot 1016 of the common carrier frequency signals ofvarious bit-loading constellations 1018 versus carrier number 1020 forthe A-BC channel path between node A and nodes B and C is shown. In thisexample, plot 1016 shows that within the A-BC channel, carrier numbersignals 1, 2 and 8 may transmit at a constellation size of 128 QAM,carrier number signals 4 and 6 may transmit at a constellation size of64 QAM, and carrier number signals 3, 5 and 7 are OFF. These carriernumber signal values are the result of comparing the carrier numbersignals from the AB channel in FIG. 10A and the corresponding carriernumber signals from the AC channel in FIG. 10B and choosing the lowestcorresponding modulation value for each carrier number. The resultingcommon carrier frequency signals in FIG. 10C graphically representsignals utilizing the common bit-loaded modulation scheme. These signalswould be able to transmit information from node A to node B and node Csimultaneously.

FIG. 11 shows a flowchart 1100 illustrating the method performed by theBCN shown in FIG. 3. In FIG. 11, the process starts in step 1102. Instep 1104, a transmitting node transmits a probe signal from thetransmitting node to a plurality of receiving nodes. In response, thereceiving nodes receive the probe signal from the transmitting node. Instep 1106, a receiving node of the plurality of receiving nodes receivesthe probe signal through the appropriate channel path of transmission.The receiving node then determines the transmission characteristics ofthe channel path from the transmitting node to the receiving node instep 1108 and in response to the determined transmission characteristicsof the channel path, the receiving node determines a bit-loadedmodulation scheme for the transmission characteristics of the channelpath in step 1110. It is appreciate by those skilled in the art that thetransmission characteristics of the channel path may be determined bymeasuring the metric values of the channel path. Examples of the metricvalues may include the signal-to-noise ratio (also known as the “SNR”and “S/N”) and/or the bit-error rate (“BER”) or product error rate(PER), or power level or similar measurement of the received signal atthe corresponding remote device. Additionally, other signal performancemetric values are also possible without departing from the scope of theinvention.

The receiving node then, in step 1112, transmits a response signal tothe transmitting node, informing the transmitting node of therecently-determined bit-loaded modulation scheme.

The transmitting node then receives a plurality of response signals, instep 1114, from the corresponding receiving nodes wherein each of theresponse signals informs the transmitting node of the correspondingbit-loaded modulation scheme determined by each of the plurality ofreceiving nodes. In response to receiving the plurality of responsesignals, the transmitting node, in step 1116, compares the plurality ofbit-loaded modulation schemes from the corresponding received pluralityof response signals and, in step 1118, determines the common bit-loadedmodulation scheme. Once the transmitting node determines the commonbit-loaded modulation scheme, the transmitting node, in step 1120,transmits a broadcast signal relaying the common bit-loaded modulationscheme to the plurality of receiving nodes. This broadcast signal mayeither contain handshake information from the transmitting node to theplurality of receiving nodes or it may actually be a communicationmessage containing information such as video, music, voice and/or otherdata.

In decision step 1122, if all the nodes in BCN have performed thehandshake process that determines the common bit-loaded modulationscheme in steps 1102 through 1120, the handshake process is complete andprocess ends in step 1124, at which time the BCN may begin to freelytransmit information between the various nodes. If instead, there arestill nodes in the BCN that have not performed the handshake processthat determines the common bit-loaded modulation scheme in steps 1102through 1120, the process then returns to step 1126. In step 1126, theBCN selects the next node in the BCN and the process steps 1102 to 1122repeat again. Once all the nodes in the BCN have preformed the handshakeprocess, the handshake process is complete and process ends in step 1124at which time the BCN may begin to freely transmit information betweenthe various nodes.

The process in FIG. 11 may be performed by hardware or software. If theprocess is performed by software, the software may reside in softwarememory (not shown) in the BCN. The software in software memory mayinclude an ordered listing of executable instructions for implementinglogical functions (i.e., “logic” that may be implemented either indigital form such as digital circuitry or source code or in analog formsuch as analog circuitry or an analog source such as an analogelectrical, sound or video signal), may selectively be embodied in anycomputer-readable (or signal-bearing) medium for use by or in connectionwith an instruction execution system, apparatus, or device, such as acomputer-based system, processor-containing system, or other system thatmay selectively fetch the instructions from the instruction executionsystem, apparatus, or device and execute the instructions. In thecontext of this document, a “computer-readable medium” and/or“signal-bearing medium” is any means that may contain, store,communicate, propagate, or transport the program for use by or inconnection with the instruction execution system, apparatus, or device.The computer readable medium may selectively be, for example but notlimited to, an electronic, magnetic, optical, electromagnetic, infrared,or semiconductor system, apparatus, device, or propagation medium. Morespecific examples, that is “a non-exhaustive list” of thecomputer-readable media, would include the following: an electricalconnection (electronic) having one or more wires, a portable computerdiskette (magnetic), a RAM (electronic), a read-only memory “ROM”(electronic), an erasable programmable read-only memory (EPROM or Flashmemory) (electronic), an optical fiber (optical), and a portable compactdisc read-only memory “CDROM” (optical). Note that the computer-readablemedium may even be paper or another suitable medium upon which theprogram is printed, as the program can be electronically captured, viafor instance, optical scanning of the paper or other medium, thencompiled, interpreted or otherwise processed in a suitable manner ifnecessary, and then stored in a computer memory.

While various embodiments of the invention have been described, it willbe apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof this invention.

What is claimed is:
 1. A method for communication, the methodcomprising: transmitting a probe signal from a transmitting node withina plurality of nodes to receiving nodes within the plurality of nodes;receiving a response signal from each of the receiving nodes, whereineach response signal includes a bit-loading modulation scheme determinedby a corresponding receiving node; comparing the bit-loading modulationschemes from the received response signals; determining a commonbit-loading modulation scheme based on comparing the bit-loadingmodulation schemes from the received response signals; and transmittinga broadcast signal from the transmitting node to the receiving nodes,wherein the broadcast signal utilizes the common bit-loading modulationscheme.
 2. The method of claim 1, further including: receiving the probesignal at one receiving node of the receiving nodes through a channelpath of transmission; determining the transmission characteristics ofthe channel path at the one receiving node; and transmitting a responsesignal from the one receiving node to the transmitting node.
 3. Themethod of claim 2, wherein the transmission characteristics of thechannel path are determined by measuring the signal-to-noise (“SNR”)characteristics of the received probe signal at the one receiving node,and further including generating the response signal, wherein theresponse signal utilizes a bit-loading modulation scheme that isgenerated by the one receiving node in response to determining thetransmission characteristics of the channel path.
 4. The method of claim2, wherein the transmission characteristics of the channel path aredetermined by measuring the bit-error rate (“BER”) characteristics ofthe received probe signal at the one receiving node.
 5. The method ofclaim 4, further including generating the response signal, wherein theresponse signal utilizes a bit-loading modulation scheme that isgenerated by the one receiving node in response to determining thetransmission characteristics of the channel path.
 6. The method of claim2, wherein the transmission characteristics of the channel path aredetermined by measuring the product-error rate (“PER”) characteristicsof the received probe signal at the one receiving node, and furtherincluding generating the response signal, wherein the response signalutilizes a bit-loading modulation scheme that is generated by the onereceiving node in response to determining the transmissioncharacteristics of the channel path.
 7. The method of claim 1, whereinat least one bit-loading modulation scheme utilizes a quadrature phaseshift keying (“QPSK”) modulation scheme.
 8. The method of claim 1,wherein at least one bit-loading modulation scheme utilizes quadratureamplitude modulation (“QAM”).
 9. The method of claim 8, wherein at leastone bit-loading modulation scheme is chosen from the group essentiallyconsisting of 64 QAM modulation, 128 QAM modulation, 256 QAM modulation,512 QAM modulation and 1024 QAM modulation.
 10. A non-transitorycomputer-readable medium having software for communication, thenon-transitory computer-readable medium comprising: logic configured fortransmitting a probe signal from a transmitting node within theplurality of nodes to receiving nodes within the plurality of nodes;logic configured for receiving a response signal from each of thereceiving nodes, wherein each response signal includes a bit-loadingmodulation scheme determined by a corresponding receiving node; logicconfigured for comparing the bit-loading modulation schemes from thereceived response signals; logic configured for determining the commonbit-loading modulation scheme based on comparing the bit-loadedmodulation schemes from the received response signals; and logicconfigured for transmitting a broadcast signal from the transmittingnode to the receiving nodes, wherein the broadcast signal utilizes thecommon bit-loading modulation scheme.
 11. The non-transitorycomputer-readable medium of claim 10, further including: logicconfigured for receiving the probe signal at one receiving node of thereceiving nodes through a channel path of transmission; logic configuredfor determining the transmission characteristics of the channel path atthe one receiving node; and logic configured for transmitting a responsesignal from the one receiving node to the transmitting node.
 12. Thenon-transitory computer-readable medium of claim 11, wherein thetransmission characteristics of the channel path are determined by logicconfigured for measuring the signal-to-noise (“SNR”) characteristics ofthe received probe signal at the one receiving node, and furtherincluding logic configured for generating the response signal, whereinthe response signal utilizes a bit-loading modulation scheme that isgenerated by the one receiving node in response to determining thetransmission characteristics of the channel path.
 13. The non-transitorycomputer-readable medium of claim 10, wherein the transmissioncharacteristics of the channel path are determined by logic configuredfor measuring the bit-error rate (“BER”) characteristics of the receivedprobe signal at the one receiving node.
 14. The non-transitorycomputer-readable medium of claim 13, further including logic configuredfor generating the response signal, wherein the response signal utilizesa bit-loading modulation scheme that is generated by the one receivingnode in response to determining the transmission characteristics of thechannel path.
 15. The non-transitory computer-readable medium of claim10, wherein the transmission characteristics of the channel path aredetermined by logic configured for measuring the product-error rate(“PER”) characteristics of the received probe signal at the onereceiving node, and further including logic configured for generatingthe response signal, wherein the response signal utilizes a bit-loadingmodulation scheme that is generated by the one receiving node inresponse to determining the transmission characteristics of the channelpath.
 16. A network for communicating between nodes in the network, thenetwork comprising: a transmitting node, the transmitting node capableof sending a probe signal; receiving nodes, wherein each of thereceiving nodes is capable of transmitting a response signal in responseto receiving the probe signal, wherein each response signal includes abit-loading modulation scheme, wherein each bit-loading modulationscheme is determined by a respective receiving node; wherein thetransmitting node is capable of determining the common bit-loadingmodulation scheme from the response signals based on comparing thebit-loaded modulation schemes; and wherein a first receiving node of thereceiving nodes is capable of: receiving the probe signal at the firstreceiving node through a channel path of transmission; determining thetransmission characteristics of the channel path at the first receivingnode; and transmitting a response signal, of the of response signals,from the receiving node to the transmitting node.
 17. The network ofclaim 16, wherein the first receiving node is capable of determining thetransmission characteristics of the channel path by measuring thesignal-to-noise (“SNR”) characteristics of the received probe signal atthe first receiving node.
 18. The network of claim 17, wherein the firstreceiving node is capable of generating the response signal, wherein theresponse signal utilizes a bit-loading modulation scheme that isgenerated by the first receiving node in response to determining thetransmission characteristics of the channel path.
 19. The network ofclaim 16, wherein the first receiving node is capable of determining thetransmission characteristics of the channel path by measuring the biterror rate (“BER”) characteristics of the received probe signal at thefirst receiving node.
 20. The network of claim 19, wherein the firstreceiving node is capable of generating the response signal, wherein theresponse signal utilizes a bit-loading modulation scheme that isgenerated by the first receiving node in response to determining thetransmission characteristics of the channel path.
 21. The network ofclaim 16, wherein the first receiving node is capable of determining thetransmission characteristics of the channel path by measuring theproduct-error rate (“PER”) characteristics of the received probe signalat the first receiving node, and wherein the first receiving node iscapable of generating the response signal, wherein the response signalutilizes a bit-loading modulation scheme that is generated by the firstreceiving node in response to determining the transmissioncharacteristics of the channel path.
 22. A network for communicatingbetween a plurality of nodes in the network, the network comprising: atransmitting node, the transmitting node having means for sending aprobe signal; and receiving nodes, wherein each of the receiving nodeshas means for transmitting a response signal in response to receivingthe probe signal, wherein each response signal includes a bit loadingmodulation scheme, wherein each bit-loading modulation scheme isdetermined by a receiving node; and wherein the transmitting nodeincludes means for determining a common bit-loading modulation schemebased on comparing the bit-loading modulation schemes; wherein a firstreceiving node of the receiving nodes includes: means for receiving theprobe signal at the first receiving node through a channel path oftransmission; means for determining the transmission characteristics ofthe channel path at the first receiving node; and means for transmittinga response signal, of the response signals, from the receiving node tothe transmitting node.
 23. The network of claim 22, wherein the firstreceiving node includes means for determining the transmissioncharacteristics of the channel path by measuring the signal-to-noise(“SNR”) characteristics of the received probe signal at the firstreceiving node, and wherein the first receiving node includes means forgenerating the response signal, wherein the response signal utilizes abit-loading modulation scheme that is generated by the first receivingnode in response to determining the transmission characteristics of thechannel path.
 24. A network for communicating between nodes in thenetwork, the network comprising: means for transmitting a probe signalfrom a transmitting node to receiving nodes within the plurality ofnodes; means for receiving a response signal from each of the receivingnodes, wherein each response signal includes a bit-loading modulationscheme determined by a corresponding receiving node; means for comparingthe bit-loading modulation schemes from the corresponding receivedresponse signals; means for determining a common bit-loading modulationscheme based on comparing the bit-loading modulation schemes; and meansfor transmitting a broadcast signal from the transmitting node to thereceiving nodes, wherein the broadcast signal utilizes the commonbit-loading modulation scheme.
 25. The network of claim 24, wherein theprobe signal utilizes a bit-loading modulation scheme that is capable ofbeing received by all the receiving nodes.
 26. The network of claim 24,further including: means for receiving the probe signal at a firstreceiving node through a channel path of transmission; means fordetermining the transmission characteristics of the channel path at thefirst receiving node; and means for transmitting a response signal fromthe first receiving node to the transmitting node.
 27. The network ofclaim 26, wherein the first receiving node includes means fordetermining the transmission characteristics of the channel path bymeasuring the signal-to-noise (“SNR”) characteristics of the receivedprobe signal at the first receiving node.
 28. The network of claim 27,further including means for generating the response signal, wherein theresponse signal utilizes a bit-loading modulation scheme that isgenerated by the first receiving node in response to determining thetransmission characteristics of the channel path.
 29. The network ofclaim 26, wherein the first receiving node includes means fordetermining the transmission characteristics of the channel path bymeasuring the bit error rate (“BER”) characteristics of the receivedprobe signal at the first receiving node.
 30. The network of claim 29,further including means for generating the response signal, wherein theresponse signal utilizes a bit-loading modulation scheme that isgenerated by the first receiving node in response to determining thetransmission characteristics of the channel path.
 31. The network ofclaim 26, wherein the first receiving node includes means fordetermining the transmission characteristics of the channel path bymeasuring the product-error rate (“PER”) characteristics of the receivedprobe signal at the first receiving node.
 32. The network of claim 24,wherein each bit-loading modulation scheme utilizes a quadrature phaseshift keying (“QPSK”) modulation scheme.
 33. The network of claim 24,wherein each bit-loading modulation scheme utilizes quadrature amplitudemodulation (“QAM”) scheme.
 34. The network of claim 33, wherein eachbit-loading modulation scheme is chosen from the group essentiallyconsisting of 64 QAM modulation, 128 QAM modulation, 256 QAM modulation,512 QAM modulation and 1024 QAM modulation.